1. Field of the Invention
The present invention relates to the field of adapters for permitting installation of a fireplace insert within a fireplace, and more particularly to an adapter useful in association with a poured flue within the fireplace chimney.
2. Description of the Prior Art
The use of fireplace inserts has become increasingly popular due to the advantages of such inserts, for example with respect to heating efficiency. Conventional fireplaces frequently create strong drafts which draw heat up from the room and through the chimney rather than contributing heat to the room. Fireplace inserts can be designed to be installed within an existing fireplace, and adapted to use the chimney as the flue for the insert. The resulting adaptation provides a system which has the advantages of comprising an efficient heating system with good aesthetics and using similar fuel, while overcoming some of the disadvantages associated with the prior fireplace unit.
In order to install a fireplace insert, it is necessary to provide for adapting the chimney to receive the flue extending from the insert. In general, there is usually provided a plate which substantially encloses the bottom of the chimney, while providing an aperture to which the insert flue connects. In some installations, the lower end of the chimney is closed off with poured concrete.
In one known system, a piece of hard rubber or plywood is positioned at the bottom of the chimney and the concrete is poured thereon. Provision is made for forming an aperture within the poured liner for reception of the flue from the fireplace insert or other woodburning appliance. Most of the time, the pour is made as close to the top of the woodburning appliance as possible, and no connector is used between the appliance and the flue. Another approach has been to use an increaser (such as an 8 to 10 inch round conduit) and embedding the larger portion within the pour. The insert flue is then connected to the bottom portion of the increaser, but this will create problems due to expansion and contraction of the metal. Also, the connection is difficult to make because this approach does not employ a slip connector.
There has remained a need to have a method for installing a poured flue adapter within a fireplace which provides a proper connection between the flue of the woodburning appliance and the poured liner. The connection desirably needs to be one which is easily accomplished and which avoids problems which could occur due to expansion and contraction of different metal components.
In U.S. Pat. No. 4,026,265 issued to Enriquez on May 31, 1977, there is described a portable fireplace heating unit for installation within an existing fireplace. The Enriquez Patent describes different types of damper adapters for connecting the unit with the existing fireplace. The connection is provided by means of an adapter plate and an insert mounted thereto for connection with a damper flue conduit. The direct interconnection of these various plates and conduits can introduce the problems previously mentioned regarding expansion and contraction of metal components at different temperatures.
Other flue adapters which connect with the chimney in similar fashions are disclosed in U.S. Pat. Nos. 4,527,541 issued to Roberts on July 9, 1985; 2,791,213 issued to Golding on May 7, 1957; and 4,424,794 issued to Paige on Jan. 10, 1984.
The use of insulation material between a furnace and a flue collar is shown in U.S. Pat. No. 4,261,325 issued to Duncan, et al. on Apr. 14, 1981. The flue collar includes a parametric flange which defines a shoulder received against an annular insulating member and the surface of the stove. A similar configuration for a furnace having a heat exchanger is described in U.S. Pat. No. 3,940,837 issued to Wiese on Mar. 2, 1976.